Copaiba essential oil carried in a self-nanoemulsifying drug delivery system improves adjuvant-induced arthritis in rats.

Objectives: Copaiba essential oil (CEO) is obtained through the distillation of copaiba balsam and has been used in the traditional medicine to treat inflammatory conditions. However, the highly lipophilic nature of CEO restricts its pharmaceutical use. This study evaluated the effect of CEO, carried in a self-nanoemulsifying drug delivery system (SNEDDS), on articular and systemic inflammation and liver changes in Holtzman rats with Freund's adjuvant-induced arthritis.

Methods: Healthy and arthritic rats received orally for 18 days the non-formulated CEO and the one carried in a self-nanoemulsifying drug delivery system (FSNEDDS), both at doses of 50 and 100 mg/kg. The oral bioavailability of FSNEDDS was determined in healthy rats by quantifying the levels of β-caryophyllene in the plasma.

Key findings: FSNEDDS exhibited more than three times greater oral bioavailability compared to non-formulated CEO. This phenomenon allowed FSNEDDS (100 mg/kg) to effectively reduce adjuvant-induced articular and systemic inflammation and oxidative stress in arthritic rats at a dose four times lower than copaiba balsam and β-caryophyllene. Furthermore, FSNEDDS did not alter the serum markers of liver damage, hepatic morphometry, and liver gluconeogenesis in healthy rats.

Conclusion: FSNEDDS was effective against arthritis in rats, and unlike copaiba balsam, it does not exhibit hepatotoxicity, suggesting it could serve as a phytotherapeutic alternative in the treatment of rheumatoid arthritis.